Preparation method of Au-SnOX (OH) Y nano material, formaldehyde gas sensor and application

Abstract

The invention belongs to the technical field of semiconductor gas sensors, and particularly relates to a preparation method of an Au-SnOX (OH) Y nano material, a formaldehyde gas sensor and application. The preparation method of the Au-SnOX (OH) Y nano material comprises the following steps: S1, carrying out precipitation-heat treatment on a SnCl4 solution to obtain SnOX (OH) Y powder; and S2, a chloroauric acid tetrahydrate solution and SnOX (OH) Y powder are taken, and gold is loaded on SnOX (OH) Y through a chemical reduction method to form the Au-SnOX (OH) Y nano material. The SnOX (OH) Y is firstly prepared, then Au is loaded to form the Au-SnOX (OH) Y nano material, and the formaldehyde gas sensor is further formed, so that the working temperature of low-concentration formaldehyde gas is reduced to 100 DEG C, the selectivity of the formaldehyde gas can be improved, and efficient and accurate detection of the concentration of the formaldehyde gas is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor gas sensors, and specifically relates to an Au-SnO X (OH) Y Preparation methods of nanomaterials, formaldehyde gas sensors and applications. Background Art

[0002] Formaldehyde is a common harmful gas, a colorless organic compound with a pungent odor. It is a protoplasmic toxic substance that can bind to proteins. When high concentrations of formaldehyde are inhaled, it can cause strong irritation to the respiratory tract, eyes and skin, leading to symptoms such as edema, tingling, and headaches. When the skin comes into direct contact with formaldehyde, it can cause allergic dermatitis, spots, and even necrosis. Formaldehyde can even cause gene mutations. Therefore, formaldehyde has been listed as a Class 1 carcinogen.

[0003] At present, the sources of formaldehyde are quite wide, so in order to reduce environmental pollution and protect human health, it is necessary to effectively monitor formaldehyde indoors, in complex environments, and in industrial production. There are many methods for formaldehyde detection, such as using gas sensors to monitor the formaldehyde content in the environment; however, most formaldehyde gas sensors require a high operating temperature of 300°C, and the high temperature of 300°C accelerates the aging of the sensor, and the selectivity of the sensor is also poor; at this stage, SnO 2 As a typical n-type semiconductor material, it has been widely used in the sensor field, but it has problems such as high operating temperature and poor selectivity, which greatly limits its scope of use. Summary of the invention

[0004] In order to solve the shortcomings of the existing formaldehyde gas sensor, such as high operating temperature and poor selectivity, the present invention provides an Au-SnO X (OH) Y Preparation methods of nanomaterials, formaldehyde gas sensors and applications.

[0005] The present invention first prepares SnO X (OH) Y , and then loaded with Au to form Au-SnO X (OH) Y Nanomaterials; and then combined with Ag-Pd electrode sheets to form a formaldehyde gas sensor, which is used for formaldehyde gas monitoring and reduces the operating temperature of low-concentration formaldehyde gas to 100°C; it can also improve the selectivity for formaldehyde gas and achieve efficient and accurate formaldehyde detection.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] An Au-SnO X (OH) YThe method for preparing a nano material comprises the following steps:

[0008] S1. Preparation of SnO X (OH) Y

[0009] SnCl 4 The solution was precipitated and heat treated to obtain SnO X (OH) Y powder;

[0010] S2. Synthesis of Au-SnO X (OH) Y Nanomaterials

[0011] Take tetrahydrate chloroauric acid solution and the SnO X (OH) Y Powder, gold loaded on SnO by chemical reduction X (OH) Y Au-SnO X (OH) Y Nanomaterial; the Au-SnO X (OH) Y Among nanomaterials, SnO X (OH) Y The mass ratio to Au is 100:(0.8-1.2).

[0012] It is further defined that in step S1, SnO is prepared X (OH) Y The process is:

[0013] S1.1、SnCl 4 ·5H 2 O was dissolved in ethanol and stirred evenly, then ammonia solution was slowly added until pH = 8-9, and a white transparent block sample was obtained after stirring, washing and drying;

[0014] S1.2: The white transparent block sample in step S1.1 is ground and heat treated to obtain SnO X (OH) Y powder.

[0015] It is further defined that in step S1.1, the stirring time is 23h to 25h; the drying temperature is 75°C to 85°C; and the drying time is 11h to 13h.

[0016] It is further defined that in step S1.2, the heat treatment is carried out at 295°C to 305°C N 2 Treat in atmosphere for 2h to 3h.

[0017] It is further defined that in step S2, Au-SnO is synthesized X (OH) Y The process of nanomaterials is:

[0018] SnO X (OH) Y The powder is dissolved in water; then tetrahydrate chloroauric acid solution and sodium borohydride solution are added; stirred for 1h to 2h, washed and dried to obtain Au-SnO X (OH) Y Nanomaterials.

[0019] Using the Au-SnO X (OH) Y Au-SnO prepared by the method for preparing nanomaterials X (OH) Y Nanomaterials.

[0020] A formaldehyde gas sensor, comprising an Ag-Pd electrode sheet and a gas-sensitive material coated on the Ag-Pd electrode sheet, wherein the gas-sensitive material is the Au-SnO X (OH) Y Nanomaterials.

[0021] The formaldehyde gas sensor is used in formaldehyde gas concentration detection.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. The present invention uses precipitation-heat treatment method to obtain SnO X (OH) Y SnO(OH) 2 and SnO 2 After loading Au, Au-SnO X (OH) Y Nanomaterials; Au-SnO X (OH) Y It is alkaline tin oxide quantum dots with a diameter of only 2.8nm, and the loaded gold produces a plasma resonance effect after being excited by light, thereby promoting the adsorption and desorption of formaldehyde; therefore, when using Au-SnO X (OH) Y After the nanomaterials are formed into a formaldehyde gas sensor, the operating temperature of the formaldehyde gas sensor for low-concentration formaldehyde gas can be reduced to 100°C, which can improve the selectivity for formaldehyde gas and achieve efficient and accurate detection of formaldehyde gas concentration.

[0024] 2. Au-SnO provided by the present invention X (OH) YThe nanomaterial, after being excited by 535nm visible light, accelerates the response recovery time, improves the sensor response value, and has high response and good selectivity to low concentration formaldehyde gas.

[0025] 3. Au-SnO prepared by the present invention X (OH) Y Nanomaterials have smaller particle size, better dispersibility, loose and porous structure, which are conducive to the adsorption and diffusion of gases. They are easy to make, small in size and suitable for mass production.

[0026] 4. The present invention uses chemical reduction method to load trace Au nanoclusters on SnO X (OH) Y The surface of the material significantly improves the response value to formaldehyde and reduces its operating temperature. The addition of visible light excitation greatly shortens the response recovery time, making it have good long-term stability and selectivity.

[0027] 5. The present invention successfully prepared Au-SnO by precipitation-heat treatment method X (OH) Y Nanomaterials have simple synthesis methods and low costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 XRD patterns of different materials; (a) Au-SnO X (OH) Y XRD patterns of sensitive materials; (b) pure SnO X (OH) Y XRD patterns of sensitive materials;

[0029] Figure 2 SnO X (OH) Y Performance test results of sensitive materials; (ac) TEM images at different magnifications; (de) EDS spectrum: distribution of Sn and Au elements;

[0030] Figure 3 Au-SnO X (OH) Y Performance test results of sensitive materials; (ac) TEM images at different magnifications; (de) EDS spectrum: distribution of Sn and Au elements;

[0031] Figure 4 SnO X (OH) Y The sensor's response value to 100ppm formaldehyde at 90-150℃;

[0032] Figure 5 Au-SnO X (OH)Y The sensor is 100ppm Au-SnO at 90-150℃. X (OH) Y Comparison of the sensor's response to 100ppm formaldehyde with an external 535nm light.

[0033] Figure 6 Au-SnO X (OH) Y The best response diagram of external visible light to 100ppm formaldehyde and its response recovery time;

[0034] Figure 7 Au-SnO X (OH) Y The best response diagram of external visible light to 1ppm formaldehyde and its response recovery time;

[0035] Figure 8 Au-SnO X (OH) Y Competitive adsorption curve of formaldehyde gas under complex atmosphere of visible light;

[0036] Fig. 9 It is the long-term stability diagram of the sensor’s response value; DETAILED DESCRIPTION

[0037] The technical solution of the present invention is further described below through the accompanying drawings and embodiments.

[0038] Unless otherwise defined, technical or scientific terms used in the present invention shall have the common meanings understood by one having ordinary skills in the field to which the present invention belongs.

[0039] Technologies, methods, and equipment known to ordinary technicians in the relevant field may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered as part of the specification.

[0040] It should also be understood that the specific embodiments described above are only used to explain the present invention, and the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solutions and inventive concepts of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

[0041] The present invention provides an Au-SnO X (OH) Y The method for preparing a nano material comprises the following steps:

[0042] S1. Preparation of SnO X (OH) Y

[0043] SnCl 4 The solution was precipitated and heat treated to obtain SnO X (OH) Y powder;

[0044] In step S1 of the present invention, SnO is prepared X (OH) Y The process is:

[0045] S1.1、SnCl 4 ·5H 2 O was dissolved in ethanol and stirred evenly, then ammonia solution was slowly added dropwise until the pH value reached 9. A white transparent block sample was obtained after stirring, washing and drying.

[0046] In step S1.1 of the present invention, the stirring time is 23h to 25h; the drying temperature is 75°C to 85°C; and the drying time is 11h to 13h.

[0047] Preferably, the stirring time is 24 hours; the drying temperature is 80° C.; and the drying time is 12 hours.

[0048] S1.2: The white transparent block sample in step S1.1 is ground and heat treated to obtain SnO X (OH) Y powder.

[0049] The heat treatment of the present invention is carried out at 295°C to 305°C N 2 Preferably, the heat treatment is carried out at 300°C in N 2 Treat in atmosphere for 2h.

[0050] S2. Synthesis of Au-SnO X (OH) Y Nanomaterials

[0051] Take tetrahydrate chloroauric acid solution and the SnO X (OH) Y Powder, gold loaded on SnO by chemical reduction X (OH) Y Au-SnO X (OH) Y Nanomaterials.

[0052] The Au-SnO X (OH) Y Among nanomaterials, SnO X (OH) Y The mass ratio to Au is 100:(0.8-1.2).

[0053] Preferably, SnOX (OH) Y The mass ratio to Au is 100:1.

[0054] In step S2 of the present invention, Au-SnO is synthesized X (OH) Y The process of nanomaterials is: SnO X (OH) Y The powder was dissolved in water; then chloroauric acid tetrahydrate solution and sodium borohydride solution were added; stirred for 1h to 2h, washed and dried to obtain Au-SnO X (OH) Y Nanomaterials.

[0055] The present invention utilizes the above-mentioned Au-SnO X (OH) Y Au-SnO prepared by the method for preparing nanomaterials X (OH) Y Nanomaterials form formaldehyde gas sensor.

[0056] The present invention utilizes a formaldehyde gas sensor to detect the formaldehyde gas concentration.

[0057] The technical solution of the present invention is described in detail below with several groups of embodiments.

[0058] It should be noted that, unless otherwise specified, the chemicals and reagents used in the following examples are all known products purchased from the market.

[0059] Example 1

[0060] This embodiment provides an Au-SnO X (OH) Y The method for preparing a nano material comprises the following steps:

[0061] S1. Preparation of SnO X (OH) Y

[0062] SnCl 4 The solution was precipitated and heat treated to obtain SnO X (OH) Y powder.

[0063] S1.1, weigh 3.5g of SnCl 4 ·5H 2 O is dissolved in 100 ml of ethanol and stirred continuously to obtain the desired solution.

[0064] S1.2. Slowly drip 25% ammonia solution into the solution until the pH value reaches 9, and continue to stir the solution at room temperature for 24 hours to obtain a white gel.

[0065] S1.3. After repeatedly washing the white gel with deionized water and ethanol to remove impurities, the filtered white gel was placed in an oven at 80°C and dried for 12 hours to obtain a white transparent block sample.

[0066] S1.4, after the sample is fully ground into fine powder in a mortar, heat-treated in a N2 atmosphere at 300℃ for 2 hours, the temperature is naturally cooled to obtain SnO X (OH) Y .

[0067] S2. Synthesis of Au-SnO X (OH) Y Nanomaterials

[0068] S5. Add 50 ml of deionized water to a beaker and weigh a certain amount of SnO X (OH) Y Add the powder into the beaker and stir evenly, then weigh the SnO X (OH) Y The powder was added dropwise to a 1% mass ratio of tetrahydrate chloroauric acid solution into a beaker, and then an appropriate amount of sodium borohydride solution was added and stirred for 1 hour. After washing with deionized water and anhydrous ethanol to remove impurities, the obtained sample was placed in a drying oven and dried to obtain a purple, powdery Au-SnO X (OH) Y Nanomaterials.

[0069] Example 2

[0070] This embodiment uses the Au-SnO X (OH) Y Formaldehyde gas sensor is prepared using nanomaterials.

[0071] The preparation method of the formaldehyde gas sensor of this embodiment is as follows:

[0072] Au-SnO X (OH) Y The nanomaterials were ground thoroughly in a mortar, and an appropriate amount of deionized water was added as a dispersant. The paste was evenly stirred with a brush to form a paste slurry, and then a brush was dipped in an appropriate amount of the slurry and evenly applied to the Ag-Pd electrode sheet to completely cover it. After the coated electrode sheet was dried, it was placed in a crucible and heated in a muffle furnace at 300°C for 2 hours to age the electrode sheet to obtain a formaldehyde gas sensor.

[0073] In this embodiment, the Ag-Pd electrode sheet was purchased from Beijing Elite Technology Co., Ltd. The wire spacing in the Ag-Pd electrode sheet was about 200 μm, and the sensitive layer (coated Au-SnO X(OH) Y The thickness of the nanomaterial layer is about 100 μm, and the area of ​​the active area is about 40 mm 2 .

[0074] Comparative Example 1

[0075] This comparative example provides a SnO X (OH) Y Sensitive material formaldehyde gas sensor, the preparation process is as follows:

[0076] S1. Preparation of SnO x (OH) y Sensitive Materials

[0077] S1.1, weigh 3.5g of SnCl 4 ·5H 2 O is dissolved in 100 ml of ethanol and stirred continuously to obtain the desired solution.

[0078] S1.2. Slowly drip 25% ammonia solution into the solution until the pH value reaches 9, and continue to stir the solution at room temperature for 24 hours to obtain a white gel.

[0079] S1.3. After repeatedly washing the white gel with deionized water and ethanol to remove impurities, the filtered white gel was placed in an oven at 80°C and dried for 12 hours to obtain a white transparent block sample.

[0080] S1.4. Grind the sample into fine powder in a mortar and place it in a N 2 After heat treatment in atmosphere for 2 hours and then cooling naturally, SnO x (OH) y Sensitive materials.

[0081] Comparative Example 2

[0082] Using the SnO x (OH) y Sensitive materials are used to obtain formaldehyde gas sensors.

[0083] The preparation process of the gas sensor in this comparative example is as follows: SnO X (OH) Y The powder was ground thoroughly in a mortar, and an appropriate amount of deionized water was added as a dispersant. The mixture was stirred evenly with a brush to form a paste-like slurry. Then, an appropriate amount of the slurry was applied evenly to the Ag-Pd electrode sheet with a brush to completely cover it. After the coated electrode sheet was dried, it was placed in a crucible and heated in a muffle furnace at 300°C for 2 hours to age the electrode sheet to obtain SnO X (OH) YFormaldehyde gas sensor with sensitive materials.

[0084] The performance of the products prepared in the above embodiments and comparative examples was tested by experiments.

[0085] Test 1

[0086] Take the Au-SnO X (OH) Y Nanomaterials and SnO of Comparative Example 1 X (OH) Y The sensitive material is subjected to XRD analysis, and the obtained XRD pattern is as follows Figure 1 shown.

[0087] See also Figure 1 The phase composition and crystal structure of the synthesized samples were identified by X-ray diffraction analysis. X (OH) Y with SnO X (OH) Y The XRD pattern did not change.

[0088] Test 2

[0089] Take the Au-SnO X (OH) Y Nanomaterials and SnO of Comparative Example 1 X (OH) Y Sensitive materials were tested by TEM and EDS spectrum, and the results were as follows: Figure 2 and Figure 3 shown.

[0090] See also Figure 2 and Figure 3 It can be seen that the synthesized samples are composed of SnO(OH) with an average diameter of 2 to 3 nm. 2 The quantum dots are composed of a nanostructured material with no obvious morphology change before and after loading Au particles. The diameter of the gold particles is 14 to 15 nm.

[0091] Test 3

[0092] Take Example 2 based on Au-SnO X (OH) Y The formaldehyde gas sensor of Comparative Example 2 is based on SnO X (OH) Y The formaldehyde gas sensor made of sensitive materials is used to test the response value of formaldehyde.

[0093] The test process is: put the electrode sheet coated with the sample into the CGS-4TPs intelligent gas-sensitive analysis system developed by Beijing Elite Technology Co., Ltd., and use the instrument to perform gas-sensitive tests on various parameters. The test temperature is 90-150℃, and an LED light with a power of 5W and a wavelength of 535nm is applied; the test results of the formaldehyde response values ​​of the two formaldehyde gas sensors are as follows: Figure 4 and Figure 5 shown.

[0094] See also Figure 4 and Figure 5 It can be seen that: after the sample without Au loading was treated with nitrogen, the response value to 100 ppm formaldehyde was 159 at humidity RH55% and temperature 120°C; after the sample loaded with Au was treated with nitrogen, the optimal response temperature was reduced to 100°C, and the external illumination greatly increased the response value; Au loading provided more active sites for gas molecule reactions, thereby increasing the response value of the prepared gas sensor, and due to the gold ion resonance effect, the adsorption capacity of Au nanoparticles for formaldehyde was enhanced, thereby increasing the response value.

[0095] Test 4

[0096] Take Example 2 based on Au-SnO X (OH) Y The formaldehyde gas sensor has the optimal response value and response recovery time to different concentrations of formaldehyde under visible light.

[0097] The test process is: put the electrode sheet coated with the sample into the CGS-4TPs intelligent gas-sensitive analysis system developed by Beijing Elite Technology Co., Ltd., and use the instrument to perform gas-sensitive tests on various parameters. The test temperature is 100°C, and an LED light with a power of 5W and a wavelength of 535nm is applied. The best response diagram and response recovery time results for 100ppm formaldehyde are shown in the figure below. Figure 6 As shown, the best response graph and response recovery time results for 1ppm formaldehyde are as follows Figure 7 shown.

[0098] See also Figure 6 and Figure 7 It can be seen that when the formaldehyde concentration is 100ppm, Au-SnO X (OH) Y The response value is as high as 7869, and the response time and response recovery time are 1251s and 811s respectively. When the formaldehyde concentration is 1ppm, Au-SnO X (OH) Y The response value is as high as 111, and the response time and response recovery time are 263s and 181s respectively.

[0099] Test 5

[0100] Take Example 2 based on Au-SnO X (OH) Y The formaldehyde gas sensor was developed to test its adsorption of formaldehyde gas in a complex atmosphere.

[0101] The test process is: put the electrode sheet coated with the sample into the CGS-4TPs intelligent gas-sensitive analysis system developed by Beijing Elite Technology Co., Ltd., and use the instrument to perform gas-sensitive tests on various parameters. The test temperature is 100°C, and an LED light with a power of 5W and a wavelength of 535nm is applied. First, 100ppm of VOCs (acetone, methanol, ethanol, ethylene glycol, 1-butanol) are introduced, and then 50ppm of formaldehyde is introduced. The results are as follows Figure 8 shown.

[0102] See also Figure 8 It can be seen that after introducing a variety of volatile organic compounds and then introducing 50ppm formaldehyde gas after its resistance stabilizes, the sample has an obvious response, indicating that the sample has excellent selectivity for formaldehyde in a complex mixed atmosphere.

[0103] Test 6

[0104] Take Example 2 based on Au-SnO X (OH) Y The formaldehyde gas sensor was used to test its stability.

[0105] The test process is: put the electrode sheet of the coated sample into the CGS-4TPs intelligent gas-sensitive analysis system developed by Beijing Elite Technology Co., Ltd., and use the instrument to perform gas-sensitive tests on various parameters. The test temperature is 100℃, and the LED light with an external power of 5W and a wavelength of 535nm is applied. Without changing any conditions, the electrode sheet of the coated sample is tested repeatedly for 15 days; the results are as follows Fig. 9 shown.

[0106] See also Fig. 9 It can be seen that within 15 days, the response value of the sample did not change significantly and still maintained a high response value.

[0107] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the present invention, although the present invention has been described in detail with reference to the preferred embodiments. It should be understood by those skilled in the art that the technical solutions of the present invention can still be modified or replaced by equivalents, and these modifications or equivalent replacements cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. Au-SnO X (OH) Y The method for preparing a nano material is characterized in that: The following steps are involved: S1. Preparation of SnO X (OH) Y SnO was obtained by precipitation-heat treatment of SnCl4 solution. X (OH) Y powder; S2. Synthesis of Au-SnO X (OH) Y Nanomaterials Take tetrahydrate chloroauric acid solution and the SnO X (OH) Y Powder, gold loaded on SnO by chemical reduction X (OH) Y Au-SnO X (OH) Y Nanomaterial; the Au-SnO X (OH) Y Among nanomaterials, SnO X (OH) Y The mass ratio to Au is 100:(0.8-1.2).

2. The Au-SnO according to claim 1 X (OH) Y The method for preparing a nano material is characterized in that: In step S1, SnO is prepared X (OH) Y The process is: S1.1, dissolve SnCl4·5H2O in ethanol and stir evenly, then slowly drop ammonia solution until pH=8-9, stir, wash and dry to obtain a white transparent block sample; S1.2: The white transparent block sample in step S1.1 is ground and heat treated to obtain SnO X (OH) Y powder.

3. The Au-SnO according to claim 1 X (OH) Y The method for preparing a nano material is characterized in that: In the step S1.1, the stirring time is 23 h to 25 h; the drying temperature is 75° C. to 85° C.; and the drying time is 11 h to 13 h.

4. The Au-SnO according to claim 1 X (OH) Y The method for preparing a nano material is characterized in that: In step S1.2, the heat treatment is carried out in a N2 atmosphere at 295°C to 305°C for 2h to 3h.

5. The Au-SnO according to claim 1 X (OH) Y The method for preparing a nano material is characterized in that: In step S2, Au-SnO is synthesized. X (OH) Y The process of nanomaterials is: SnO X (OH) Y The powder is dissolved in water; then tetrahydrate chloroauric acid solution and sodium borohydride solution are added; stirred for 1h to 2h, washed and dried to obtain Au-SnO X (OH) Y Nanomaterials.

6. Utilizing the Au-SnO according to claim 1 X (OH) Y Au-SnO prepared by the method for preparing nanomaterials X (OH) Y Nanomaterials.

7. A formaldehyde gas sensor, characterized in that: It comprises an Ag-Pd electrode sheet and a gas-sensitive material coated on the Ag-Pd electrode sheet, wherein the gas-sensitive material is the Au-SnO X (OH) Y Nanomaterials.

8. Use of the formaldehyde gas sensor as claimed in claim 7 in formaldehyde gas concentration detection.

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